| 释义 |
reˈtarder
[f. as prec. + -er1.]
a. One who or that which checks or delays.
1644R. Baillie Lett. & Jrnls. (1841) II. 139 They have been the retarders of the Assemblie. 1688Lond. Gaz. No. 2469/2 Who were retarders, or obstructers of the Designs of the Estates. 1760S. Fielding Ophelia II. xiv, Those..sensations are great retarders of a lover's progress. 1839Civil Eng. & Arch. Jrnl. II. 122/2 The sledge or retarder..is formed like a wedge. 1971P. Gresswell Environment 264 Weed-killers or growth retarders are needed that keep rank growth in check without eliminating all wild flowers. 1980Jrnl. R. Soc. Arts Mar. 175/1 We will find ourselves sooner or later seeking..to break through that asymptote determined by nature's built-in retarders.
b. A substance which slows down a reaction or process.
1878Abney Photogr. (1881) 68 It has been in effect found that ferric sulphate is a retarder. 1946Sun (Baltimore) 7 Oct. 2/5 The meat situation may prolong the housing problem because plaster cannot be made without ‘retarder’, which is obtained from horn and hoof meal. 1967Margerison & East Introd. Polymer Chem. iv. 195 Those substances which affect the rate of the polymerization are termed inhibitors or retarders according to whether the rate is reduced to zero or to a finite value. 1974Encycl. Brit. Macropædia IV. 1076/1 The characteristics of concrete often can be improved by including admixtures in the concrete mix. In addition to set-accelerators..there are set-retarders (usually of a sugar base) that are less commonly required.
c. (See quot. 1898.)
1898W. S. Hutton Steam-Boiler Constr. (ed. 3) vi. 455 The smoke-tubes of multitubular boilers are sometimes fitted with either retarders or radiators, with the object of increasing the efficiency of the heating-surface. A retarder usually consists of a flat strip of sheet-metal twisted spirally, to compel the fuel-gases to travel through the tubes in a spiral-form. 1902Rep. Admiralty Comm. Naval Boilers §29. 15 The Committee..think it right to state that retarders will be found in many cases to render existing cylindrical boilers more efficient and economical than they are at present. 1903Sci. Amer. Suppl. 24 Jan. 22625/1 The cylindrical boilers should be fitted with retarders in the tubes. 1953J. N. Williams Boiler House Practice vii. 152 Refractory cores or retarders were employed but with only partial success as the refractory would not stand up to the temperatures which approximated to those of theoretical combustion.
d. Railways. An arrangement of rails placed inside and parallel to the running rails in a shunting yard which may be moved sideways so as to act as a brake on the flanges of wagon wheels.
1937W. G. Raymond Elem. Railroad Engin. (ed. 5) xiv. 186 The car retarder is a device to control the speed of a moving freight car. 1966G. F. Allen B.R. after Beeching viii. 248 Further B.R. applications of this ingenious device may be confined to the outer ends of reception sidings in existing yards already equipped with electronically-controlled, clamp-type retarders, to improve the speed control of shunted wagons after they have left the hump area. 1969H. R. Broadbent Introd. Railway Braking ii. 11 The retarders used in marshalling yards do not come under the heading of train-operated brakes. |